Anytime you focus on bad things that happened in the past you can very easily fall into depression. I struggle with this quite often. The key is acceptance and letting go of the past. Once you do that you can move forward in your life and start healing. Theres nothing you can do to change the past.... but you can make a wonderful new life now for yourself & your daughter without him. Put all your focus on the things you can do today that make you happy. When you focus on him and what he did to you, you are still giving him the power he had over you. Then of course you will be majorly depressed... anyone would be.
I know its hard and it takes alot of monitoring your thoughts and actions... but the end result and YOU are worth it!!